Author(s): Peeters Bert, Van Blokland Gijsjan
The EU Directive 2015/996 (CNOSSOS-EU) provides separate calculation models for the noise emission from road traffic, rail traffic, aircraft and industrial sources. The road noise emission model is comprehensive yet straightforward to implement. The Directive provides the formulas for calculating the noise emission, as well as default sound power coefficients: values that describe the noise emissions at 70 km/h and speed coefficients to calculate the levels for other vehicle speeds.\n\nThe sound power coefficients have been derived from roadside noise measurements of passing vehicles. The pass-by noise is attributed to a single source height, using a calculation of the propagation from microphone to source. The current CNOSSOS-EU propagation model is, however, different from the Harmonoise model used to establish the sound power coefficients provided. There is currently a mismatch, therefore, between the CNOSSOS road noise emission factors and the propagation model.\n\nThe paper explains the acoustic description of both propagation models in the near-field, including the effect of the reflection of sound waves on the road surface. The results show that the current sound power coefficients in the 2015/996 Directive are a significant underestimation of the actual noise emission, with a magnitude depending on frequency. \nA procedure to establish correct coefficients for CNOSSOS is provided, and a new set of coefficients for the average European vehicle fleet are proposed. The measurement and analysis procedure given in this paper may also be used to update the noise emission factors in the future, or to derive regional values for individual Member States.
Name: Mr Bert Peeters